Ink-jet recording techniques are recording techniques, wherein a fine ink droplet is caused to fly with various actuation principles and adhered to a recording material, such as paper, and wherein an image, a letter, or the like, is thus recorded. The ink-jet recording techniques have advantages in that the printing is capable of being performed quickly with low noise. As ink-jet printers used for the ink-jet recording techniques, there have been known a serial head type ink-jet printer, wherein an ink-jet head moves and scans in a direction intersecting with the direction of conveyance of the recording material, and a line head type ink-jet printer, wherein the ink-jet heads are secured and arrayed in a direction intersecting with the direction of conveyance of the recording material.
With the serial head type ink-jet printer, while the recording material is being conveyed, the ink-jet head is moved in the direction intersecting perpendicularly to the direction of conveyance of the recording material, and the image is thus formed. Though the serial head type ink-jet printer is easy to perform maintenance, since the ink-jet head is actuated for the reciprocal movements, it is not always easy to cope with a quick printing operation.
With the line head type ink-jet printer, a secured type recording head composed of ink-jet heads arrayed so as to stand side by side with respect to the direction intersecting perpendicularly to the direction of conveyance of the recording material is used, and the recording operation is performed only with sub-scanning for feeding the recording material in the direction of conveyance. While the recording of one line in one lot by the jetting-out of the ink composition from the ink-jet heads is being performed successively, paper feed by a predetermined distance is performed, and an image is thus recorded over the entire area of the recording material. Therefore, the line head type ink-jet printer appropriate for a quick printing operation. However, since the ink jet heads are secured, it is not always possible to perform maintenance easily.
In cases where an aqueous type ink composition utilizing water as a principal solvent is used for the ink-jet recording techniques described above, the phenomena, such as ink composition thickening and coloring material deposition, occur in the vicinity of nozzles due to evaporation of water contained in the ink composition, and the problems are encountered in that the ink composition jetting-out performance becomes bad, particularly, the intermittent jetting-out performance becomes bad.
In order for the aforesaid problems to be solved, from the aspect of the apparatus for jetting out the ink composition, techniques for actuating piezoelectric devices to an extent such that the ink composition may not be jetted out, vibrating meniscuses, thereby stirring the ink composition, and suppressing the ink composition thickening are described in, for example, patent literatures 1 and 2. Also, a technique in the so-called serial type ink-jet recording apparatus, wherein ink composition droplets are jetted out to perform the printing operation at the time at which the head has moved to a maintenance position, or the like, and wherein the lowering of the ink composition jetting-out performance is thereby prevented, is described in a patent literature 3. Further, an apparatus for detecting an alteration of ink composition viscosity, performing recovery processing for a thickened liquid-state when necessary, performing jetting-out actuation or print data compensation in accordance with the viscosity of the ink composition, and thereby coping with the lowering of the jetting-out performance is described in a patent literature 4.
However, with the techniques for actuating the piezoelectric device as described in the patent literatures 1 and 2, the problems are encountered in that electric power requirement is not kept low. Also, in cases where the preliminary jetting-out operation is performed frequently as in the technique described in the patent literature 3, the problems occur in that the ink composition is wasted. Further, though the techniques described in the patent literatures 1 to 4 are applicable to the serial head type ink-jet printer, it is not always possible for the aforesaid techniques to be applied to the line head type ink-jet printer since, for example, it is not easy to locate a preliminary jetting-out mechanism.
In order for the lowering of the intermittent jetting-out performance to be suppressed, aqueous type ink compositions having been improved have also been known. An aqueous type ink composition containing acetylene glycol is proposed in a patent literature 5. Also, an aqueous type ink composition containing a decaglycerol fatty acid ester is proposed in a patent literature 6.    Patent literature 1: Japanese Unexamined Patent Publication No. 2002-283546    Patent literature 2: Japanese Unexamined Patent Publication No. 2004-202708    Patent literature 3: Japanese Unexamined Patent Publication No. 8 (1996)-118674    Patent literature 4: Japanese Unexamined Patent Publication No. 2004-299341    Patent literature 5: Japanese Unexamined Patent Publication No. 54 (1979)-005871    Patent literature 6: Japanese Unexamined Patent Publication No. 4 (1992)-008777